Configuring a voice test – H3C Technologies H3C S7500E Series Switches User Manual
Page 38
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To do…
Use the command…
Remarks
Configure the source IP address of
a probe request in a test operation
source ip ip-address
Optional
By default, no source IP address is
specified.
The source IP address must be that
of an interface on the device and the
interface must be up. Otherwise, the
test will fail.
Configure common optional
parameters
Optional
Configuring a Voice Test
It is recommended not to perform an NQA UDP jitter test on known ports, namely, ports from 1 to 1023.
Otherwise, the NQA test will fail or the corresponding services of these ports will be unavailable.
A voice test is used to test voice over IP (VoIP) network status, and collect VoIP network parameters
so that users can adjust the network according the network status. The procedure of a voice test is as
follows:
1) The source (NQA client) sends voice packets of G.711 A-law, G.711 µ-law or G.729 A-law codec
type at regular intervals to the destination (NQA server).
2) The destination affixes a time stamp to each packet that it receives and then sends it back to the
source.
3) Upon receiving the packets, the source calculates the delay jitter and delay by calculating the
difference between the interval for the destination to receive two successive packets and the
interval for the source to send these two successive packets, and thus the network status can be
analyzed.
The voice parameter values that indicate VoIP network status can also be calculated in a voice test,
including:
z
Calculated Planning Impairment Factor (ICPIF): Measures attenuation of voice data in a network,
depending on packet loss and delay. A higher value represents a lower network quality.
z
Mean Opinion Scores (MOS): Measures quality of a VoIP network. A MOS value can be
evaluated by using the ICPIF value, in the range 1 to 5. A higher value represents a higher quality
of a VoIP network.
The evaluation of voice quality depends on users’ tolerance to voice quality, which should be taken
into consideration. For users with higher tolerance to voice quality, use the advantage-factor